ARRL Propagation Bulletin ARLP044 (2006)

ARLP044 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 44  ARLP044
From Tad Cook, K7RA
Seattle, WA  October 27, 2006
To all radio amateurs 

ARLP044 Propagation de K7RA

Early on Friday morning before the CQ World Wide SSB DX Contest,
conditions are stable and quiet, and after the sunspot number rose
to 50 this week following eight days of no sunspots, the average
daily sunspot number increased from nothing to 23.3. Unfortunately,
the stable quiet conditions are not expected to last through the

The predicted planetary A index for Friday through Monday, October
27-30, is 10, 20, 10 and 5. Geophysical Institute Prague calls for
unsettled conditions today, October 27, unsettled to active on
October 28, quiet to unsettled on October 29-30, and back to quiet
conditions for October 31 through November 2. Also, on Thursday
October 26, the sunspot number was back to 0. Don't be surprised if
we see no sunspots through the weekend and beyond.

With no sunspots visible, we might think of the sun as blank, but
check this photograph taken by an amateur astronomer on Thursday.
You'll see quite a bit of detail at,

An interesting observation came in from Randy Crews, W7TJ of
Spokane, Washington. He's been going through his old paper logs, and
entering the data into his logging program. Randy writes, "What is
interesting is how productive 80 and especially 160 Meters are the
year before, the year of, and especially the year following the
bottom of the sunspot cycle. DXers should really take full advantage
of the unique quiet portion of cycle 23's end, and the beginning of
cycle 24 spending extra time on the low bands for needed countries,

Good timely information, as we head into the solar minimum over the
next six to eight months.

NASA announced the successful launch of the 3D Solar Imaging
satellites on Wednesday. The mission is called STEREO, and it is
expected to render exciting 3-dimensional images of coronal mass
ejections. Read about it on the web at,

If you would like to make a comment or have a tip for our readers,
email the author at,

For more information concerning radio propagation, see the ARRL
Technical Information Service at, For a detailed
explanation of the numbers used in this bulletin see, An archive of past
propagation bulletins is at,

Sunspot numbers for October 19 through 25 were 14, 15, 16, 18, 50,
35 and 15 with a mean of 23.3. 10.7 cm flux was 69.6, 71.1, 74.7,
75.8, 76.4, 74.8, and 74.7, with a mean of 73.9. Estimated planetary
A indices were 2, 10, 15, 13, 3, 4 and 4 with a mean of 7.3.
Estimated mid-latitude A indices were 1, 9, 10, 12, 2, 3 and 4, with
a mean of 5.9.